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Miocene Current-Modified Submarine Fans in Mexican Deep-Water Areas

Abstract

In the southwestern Gulf of Mexico deep-water areas, new and newly reprocessed seismic data have revealed a series of large bed forms, with set thicknesses of 130 to 250 meters. These exhibit hummocky, oblique and shingled to parallel seismic clinoform reflections. This Miocene to Plliocene-age seismic package is interpreted to have been deposited in paleowater depths of 450 meters. Those shingled seismic reflections in offshore east Mexico are interpreted as current-modified submarine fans and associated contourite drift deposits. These bed forms may be related to strong ocean bottom currents that modified submarine fans and transported sediment to the north. Other mechanisms considered are cyclic steps of bed forms related to turbidity flows. These bed forms were identified on older seismic data, but are better imaged and interpreted on new seismic data. Plans are to map out and investigate the origin and extent of fans and contourites that extends over a large area of the Gulf of Mexico.In the Early Miocene several submarine fans systems were formed by the sediment input related to orogenic activity in Mexico. Submarine fan development persisted into the Middle Miocene due to continued uplift and erosion of the Mexican landmass. Initial contourites are small and close proximity to the deep-water fan. In the Late Miocene time, contourite drift field reached its maximum extent in the Mexican deepwater area, anchored on its southern end by a submarine mound. This mounded submarine fan is located in the offshore northeast Veracruz and can be linked to increased uplift and erosion of the Trans-Mexican volcanic belt. In the Miocene-Pliocene, the large contourite drift field begins to diminish in size and scale and is moribund by the Pliocene, with establishment of oceanic circulation similar to the present day.This research is important to understand more about the Gulf of Mexico an its petroleum potential, and also for the Miocene timeframe that is a key reservoir. The role of the changes in bottom water flow during progressive closure of the equatorial seaway separating North and South America will also be discussed